1. Field of the Invention
The present invention relates to an ultrasonic probe for and a method of acquiring a tomographic image and other graphic images to be taken from the internal organs of a human body by taking advantage of an ultrasound, and more particularly to an ultrasonic probe for and a method of acquiring a tomographic image and other graphic images to be used for the diagnosis by doctors in the hospitals.
2. Description of the Related Art
In recent years, there have been developed and used various kinds of ultrasonic probes which are designed to probe the internal organs of the human body to assist the doctors in diagnosing the human body in the hospitals. Among those ultrasonic probes, there are two types of ultrasonic probes the first one of which is constructed to be moved on while being kept in touch with the human body""s skin to probe the solid internal organs such as livers and pancreas from the outside of the human body, and the second one of which is inserted into the hollow internal organs of the human body including stomachs, rectums and vaginas to probe the hollow internal organs of the human body. Both of the forgoing ultrasonic probes are adapted to emit an ultrasonic wave to the targeted portions of the human body before receiving an ultrasonic wave echoed from the targeted portions of the human body. The ultrasonic wave is transformed by the ultrasonic probe in a conventional manner into an electric signal that is processed into a tomographic image to be displayed on a display unit.
The ultrasonic wave probe is provided at its leading end with an ultrasonic wave probe unit comprising a transducer for transducing an electric signal into and out of an ultrasonic wave, and an electromagnet motor for rotating the transducer within a predetermined rotation angle. The ultrasonic wave probe of this type provided with an ultrasonic wave probe unit as constructed in the above is disclosed in a publication such as for example a Japanese laid-open publication No. 70268/2000.
The conventional ultrasonic wave probe of this type, however, encounters such a problem that the transducer may be rotated unrestrictedly while the electromagnet motor is stopped to drive to rotate the transducer, and subject to breakage by a large shock caused by the electromagnet motor especially when the ultrasonic wave probe is dropped resulting from the fact that the transducer is directly mounted on the electromagnet motor.
The present invention is made with a view to overcoming the previously mentioned drawback inherent to the conventional ultrasonic wave probe.
It is therefore an object of the present invention to provide an ultrasonic probe which can keep the transducer from rotating by braking the electromagnet motor when the electromagnet motor is stopped. This makes it possible to protect the transducer from a large shock caused by the electromagnet motor especially when the ultrasonic wave probe is dropped
It is another object of the present invention to provide an ultrasonic probe which can prevent the transducer from rotating by actuating a brake mechanism when the electromagnet motor is stopped. This makes it possible to protect the transducer from a large shock caused by the electromagnet motor especially when the ultrasonic probe is dropped.
According to one aspect of the present invention, there is provided an ultrasonic probe, comprising: a housing; a frame structure accommodated in the housing and held stationary with respect to the housing; an electromagnet motor rotatably supported by the frame structure in the housing; a transducer fixedly supported by the electromagnet motor in the housing to transduce an ultrasonic wave to and from an electric signal; a brake mechanism fixedly supported by the frame structure in the housing and operative to assume a braking state allowing the electromagnet motor to be braked and a brake-releasing state allowing the electromagnet motor to be released from being braked. The above electromagnet motor is released from being braked by the brake mechanism when the electromagnet motor is driven to rotate while the electromagnet motor is braked by the brake mechanism when the electromagnet motor is stopped.
It is desirable that the above frame structure includes a bottom wall portion and a side wall portion integrally formed with the bottom wall portion to form a hollow chamber, and a window cover securely mounted on the side wall portion of the frame structure to form a closed chamber having the electromagnet motor received therein. The above window cover may be made of an ultrasonic wave transmission material to have the transducer transduce the ultrasonic wave to and from the electric signal.
The above window cover and the frame structure are desirably combined to define a hermetically sealed chamber filing therein a coupling liquid to assist the transducer in transducing the ultrasonic wave to and from the electric signal.
Preferably, the transducer includes a main body having a top surface, and a plurality of piezoelectric elements arranged on the top surface of the main body in spaced relationship with each other along the center axis of the electromagnet motor.
The piezoelectric elements may be in the form of a rectangular shape having a short edge extending along the center axis of the electromagnet motor.
It is desirable that the above window cover has inner and outer surfaces arcuately formed and the main body of the transducer has an outer surface arcuately formed in parallel and spaced relationship with the inner surface of the window cover.
The electromagnet motor preferably includes a rotor portion having a center axis and a pair of side surfaces, and a pair of shaft portions each having a center axis. The shaft portions may be respectively secured to the side surfaces with the center axes being respectively in alignment with the center axis of the rotor portion and rotatably supported by the frame structure.
It is desirable that the frame structure includes a base plate portion, and a pair of stand portions spaced apart from each other along with the rotation axis of the electromagnet motor. The electromagnet motor may include a rotor portion having a center axis and a pair of side surfaces, and a pair of shaft portions each having a center axis. The shaft portions may be respectively secured to the side surfaces with the center axes being respectively in alignment with the center axis of the rotor portion and rotatably supported by the frame structure. The shaft portions may be respectively rotatably supported by the stand portions of the frame structure.
The ultrasonic probe thus constructed can prevent the transducer from rotating by braking the electromagnet motor when the electromagnet motor is stopped. This makes it possible to protect the transducer from a large shock caused by the electromagnet motor especially when the ultrasonic wave probe is dropped.
According to the present invention, the electromagnet motor of the ultrasonic probe has a peripheral portion formed with a cavity. It is desirable that the brake mechanism includes a magnetic frame securely mounted on the frame structure and formed with a chamber therein, an electromagnet coil received in the chamber of the magnetic frame and partly secured to the magnetic frame. The electromagnet coil may be in the form of a cylindrical hollow shape. The brake mechanism desirably further include an electromagnet shaft partly received in the chamber of the magnetic frame in axial alignment with the electromagnet coil and supported by the magnetic frame, and a second longitudinal portion projecting inwardly of the electromagnet coil and the magnetic frame.
The electromagnet shaft may have a first longitudinal portion projecting outwardly of the magnetic frame. The electromagnet shaft may be axially movable with respect to the magnetic frame and the electromagnet coil to assume two operation states consisting of a first operation state under which the electromagnet shaft is projected to an extremely projected position with respect to the electromagnet coil and a second operation state under which the electromagnet shaft is retracted to an extremely retracted position with respect to the electromagnet coil. The brake mechanism desirably further include electromagnet shaft urging means for resiliently urging the electromagnet shaft toward the first operation state under which the first longitudinal portion of the electromagnet shaft is partly brought into engagement with the cavity of the electromagnet motor.
The ultrasonic probe thus constructed can hold the transducer from rotating by braking the electromagnet motor when the electromagnet motor is stopped. This makes it possible to protect the transducer from a large shock caused by the electromagnet motor especially when the ultrasonic wave probe is dropped.
According to the present invention, the above first longitudinal portion of the electromagnet shaft is integrally formed with a first flange portion, and the second longitudinal portion of the electromagnet shaft is integrally formed with a second flange portion, and in which the electromagnet shaft urging means is constituted by a helical coil spring disposed to surround the first longitudinal portion of the electromagnet shaft and to have one end engaged with the first flange portion and the other end engaged with the electromagnet frame.
The above electromagnet motor may be operative to assume a stop position under which the electromagnet motor is stopped with respect to the frame structure with the cavity being in opposing relationship with the first longitudinal portion of the electromagnet shaft. The ultrasonic probe according to the present invention may further comprise electromagnet motor urging means for resiliently urging the electromagnet motor toward the stop position of the electromagnet motor.
The above electromagnet motor may be operative to assume a stop position under which the electromagnet motor is stopped with respect to the frame structure with the cavity being in opposing relationship with the first longitudinal portion of the electromagnet shaft. According to the present invention, the ultrasonic probe may further comprise electromagnet motor urging means for resiliently urging the electromagnet motor in the rotation direction of the electromagnet motor toward the stop position of the electromagnet motor, and electromagnet motor stopping means for stopping the electromagnet motor from being rotated over the stop position.
It is desirable that the electromagnet motor urging means is constituted by a helical coil spring having one end secured to the electromagnet motor and the other end secured to the frame structure, and the electromagnet motor stopping means is constituted by a projected pin projecting axially outwardly of the side surface of the electromagnet motor. The projected pin preferably has a rotation path on which the projected pin is rotatable together with the electromagnet motor, and a stop member securely formed on the frame structure to project to the rotation path of the projected pin to ensure that the electromagnet motor is resiliently urged by the helical coil spring and stopped by the projected pin and the stop member under the stop state under which the cavity is in opposing relationship with the first longitudinal portion of the electromagnet shaft.
In the ultrasonic probe according to the present invention, the electromagnet motor is resiliently urged toward the stop position by the electromagnet motor urging means and stopped with respect to the frame structure with the cavity being opposing relationship with the first longitudinal portion of the electromagnet shaft regardless of the current rotation angle of the electromagnet motor to ensure to prevent the electromagnet motor from rotating.
The aforesaid brake mechanism includes a gear member having a center axis and securely mounted on the side surface of the electromagnet motor with the center axis being aligned with the center axis of the electromagnet motor, the gear member having a plurality of teeth equally spaced apart from one another in the circumferential direction of the gear member, and a plurality of recesses each arranged and disposed between the adjacent two teeth, a magnetic frame securely mounted on the frame structure and formed with a chamber therein, an electromagnet coil received in the chamber of the magnetic frame and partly secured to the magnetic frame, the electromagnet coil being in the form of a cylindrical hollow shape, an electromagnet shaft partly received in the chamber of the magnetic frame in axial alignment with the electromagnet coil and supported by the magnetic frame and in opposing relationship with the gear member, the electromagnet shaft having a first longitudinal portion projecting outwardly of the magnetic frame and a second longitudinal portion projecting inwardly of the electromagnet coil and the magnetic frame, the electromagnet shaft being axially movable with respect to the magnetic frame and the electromagnet coil to assume two operation states consisting of a first operation state under which the electromagnet shaft is projected to an extremely projected position with respect to the electromagnet coil and a second operation state under which the electromagnet shaft is retracted to an extremely retracted position with respect to the electromagnet coil, the first longitudinal portion of the electromagnet shaft having a leading end portion in the form of a pawl shape, electromagnet shaft urging means for resiliently urging the electromagnet shaft toward the first operation state under which the leading portion of the first longitudinal portion of the electromagnet shaft is partly brought into meshing engagement with one of the recesses of the gear member.
In the ultrasonic probe of the third embodiment according to the present invention, the leading portion of the electromagnet shaft is movable to be brought into and out of meshing engagement with one of the recesses of the gear member regardless of the current rotation angle of the electromagnet motor to ensure to prevent the electromagnet motor from rotating.
The aforesaid electromagnet motor may include a rotor portion having a center axis and a pair of side surfaces, and a pair of shaft portions each having a center axis, the shaft portions being respectively secured to the side surfaces with the center axes being respectively in alignment with the center axis of the rotor portion and rotatably supported by the frame structure.
The aforesaid brake mechanism may include a first electromagnet member securely mounted on the peripheral wall of the rotor portion of the electromagnet motor, a magnetic frame securely mounted on the frame structure and formed with a chamber therein, an electromagnet coil received in the chamber of the magnetic frame and partly secured to the magnetic frame, the electromagnet coil being in the form of a cylindrical hollow shape, a second electromagnet member partly received in the chamber of the magnetic frame in axial alignment with the electromagnet coil and supported by the magnetic frame to be directed toward the first electromagnet member to ensure that the first and second electromagnet members repel each other when the electromagnet coil is energized.
The aforesaid magnetic frame preferably includes a bottom wall portion securely mounted on the frame structure, and a side wall portion integrally formed with the bottom wall portion, whereby the bottom wall portion and the side wall portion of the magnetic frame and the first electromagnet member collectively define a chamber to receive the electromagnet coil, the bottom wall portion and the side wall portion of the magnetic frame and the first electromagnet member is made of a magnetic substance.
In the ultrasonic probe thus constructed, the rotor portion is stopped from rotating regardless of the current rotation angle of the electromagnet motor to ensure to prevent the transducer from rotating. Furthermore, the brake mechanism can be constructed without mechanical moving parts, thereby improving the performance and reliability of the ultrasonic probe.